Anti-deflection drain board method and apparatus

ABSTRACT

THE DEFLECTION OF A FORMING BOARD RELATIVE TO A BREAST ROLL IN A PAPERMAKING MACHINE IS CONTROLLED POSITIVELY BY THE METHOD OF THE APPLICATION OF A FORCE ALONG THE LENGTH TO THE FORMING BOARD BY BELLOWS, BY TEMPERATURE DIFFERENTIAL ACHIEVED THROUGH SEPARATE CONTAINERS FOR LIQUID, OR BY THE WEIGHT OF FLUID IN A TANK, AND DEFLECTION IN THE MACHINE DIRECTION OF MOVEMENT OF THE FORMING WIRE IS CONTROLLED BY SLIDING GUIDES.

June 15, 1971 L. M. STUEBE 3,585,105

, ANTI-DEFLEC'IION DRAIN BOARD METHOD AND APPARATUS Filed May 26, 1967 2 Sheets- Sheet 1 M/ Eb Z0 /0 y I y 1 j /6 /2 6 I, I Mm nth X 7 n 27 INV/fN'lUA.

100/5 M SVuebe June 15, 1971 L. M. STUEBE 3,585,395

ANTI-DEFLECTION DRAIN BQARD METHOD AND APPARATUS Filed May 26, 1967 2 Sheets-Sheet 2,

INVILN'IUR Zou/s M S/uebe United States Patent O 3,585,105 A'NTI-DEFLECTION DRAIN BOARD METHOD AND APPARATUS Louis M. Stuebe, Beloit, Wis., assignor to Beloit Corporation, Beloit, Wis. Filed May 26, 1967, Ser. No. 641,568 Int. Cl. D211? 1/00 US. Cl. 162211 13 Claims ABSTRACT OF THE DISCLOSURE The deflection of a forming board relative to a breast roll in a papermaking machine is controlled positively by the method of the application of a force along the length of the forming board by bellows, by temperature differential achieved through separate containers for liquid, or by the weight of fluid in a tank, and deflection in the machine direction of movement of the forming wire is controlled by sliding guides.

BACKGROUND OF THE INVENTION The present invention relates to improvements in papermaking machines and more particularly to obtaining the improved dewatering and formation of a paper web in the initial forming area at the forming board by controlling the contour or deflection of the forming board in a positive manner relative to the breast roll.

In papermaking machines a pervious forming wire passes over a breast roll to extend in a top forming run, and following the breast roll is a forming board. The breast roll will deflect along its length so that it is lower at the center than at the ends, and different factors in machine operation will change the deflection of the breast roll and will also change the deflection of the forming board. However the factors which cause these changes do not affect the breast roll and forming board in the same way. For example, one of the forces on the breast roll is the wire tension and as the wire tension is changed the deflection in the breast roll changes and this normally has no effect on the forming board. A factor which nonuni formly affects forming board and breast roll deflection is the force of the stock as it is distributed onto the wire. This force changes with the weight or quantity of stock distributed and speed of flow of the stock.

If the leading edge of the forming board is too high relative to the breast roll, the wire will have to turn severely upwardly as it comes on to the forming board edge thus tending to throw the liquid stock upwardly. If the forming board leading edge is too low relative to the breast roll it will leave a gap between the wire and the forming board, and the wire will be unsupported so that improper drainage occurs at that location. One of the substantial difliculties encountered is that the breast roll sags at its center due to the substantial weight of is lengh so that if the wire is to be supported and the proper relationship to the forming board maintained, the forming board must also be deflected downwardly in the center so that its deflection or contour is exactly the same as the breast roll. Since the forces on the breast roll change with changes in operating condition, a forming board arrangement which is proper for one operating condition will be inadequate for another operating condition when the breast roll deflection changes. The deflecting forces on the forming board make its construction difficult in that it is subjected to both downward forces due to its weight and to the stock flow and to deflection in the machine direction due to the force of oncoming water from the web hitting the board and due to the wire drag.

It is accordingly an object of the present invention to provide an improved method and structure for control- 3,585,105 Patented June 15, 1971 ling the deflection or contur of the forming board along its length so that its deflection can be accurately matched to the deflection of the breast roll and can be positively controlled independent of wire drag forces and water deflection forces.

A further object of the invention is to provide an improved forming board structure wherein its deflection can be controllably changed to match deflection of the breast roll which changes with wire tension and stock force changes and wherein an improved dewatering effect can be accomplished which provides uniform conditions completely across the machine.

A still further object of the invention is to provide an improved relationship between the forming board and breast roll so that optimum and uniform dewatering conditions occur across the machine and formation problems are avoided such as non-uniform dewatering which results in non-uniform moisture content across the machine, flocculation and unevenness of web formation, and disturbances in the uniform formation of the web from the stock.

SUMMARY OF THE INVENTION The method and apparatus of the invention include in combination with a pervious travelling forming wire having an upper web forming run, a breast roll supporting the wire at the lead end of the run, a forming board means having an upper surface extending across beneath the wire following the breast roll and means for changing the contour or deflection of the board means along its length independent of other factors of machine operation.

Other objects, advantages and features will become more apparent with the teaching of the principles of the invention in connection with the disclosure of the preferred embodiments thereof in the specification, claims and drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view shown in somewhat schematic form of a portion of a papermaking machine embodying the principles of the present invention;

FIG. 2 is an exploded fragmentary showing of a portion of the mechanism of FIG. 1;

FIG. 3 is a sectional view taken substantially along line III-III of FIG. 1;

FIGS. 4 and 5 are schematic side elevational views showing the effects of improper operation such as is achieved with devices and methods heretofore available;

FIG. 6 is a fragmentary side elevational view showing another form of the invention;

FIG. 7 is a fragmentary side elevational view showing another form of the invention; and

FIG. 8 is a fragmentary sectional view taken substantially along line VIII-VIII of FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates the forming zone in the wet end of a paper machine wherein a pervious travelling forming wire 10 is stretched over a breast roll 11 and has an upper forming run receiving a stock from the slice opening of a headbox 120.

Following the breast roll 11 is a forming board means 12 which is located at an optimum position relative to the breast roll 11 and relative to the location where the stock is discharged onto the wire, but is not necessarily shown in exact size or in optimum location in the drawmgs.

The forming board 12 in FIGS. 1, 2 and 3 is shown as formed in portions or strips 13, 14 and 15 which extend across the machine and have gaps therebetween for the water being removed from the stock to flow downwardly.

A suitable saveall pan will be positioned for receiving the water.

The forming board strips 13, 14 and 15 are supported on frameork sections 16, 17 and 18 extending across the machine and having fins or webs 19 and 20 interconnecting them at laterally spaced locations.

Beneath the forming board 12 is a rigid supporting frame 23. To support the forming board in a machine direction and to resist the forces of the drag of the wire 10 across the top surfaces of the forming board as well as to resist the force of the water as it is drawn downwardly against the forming board, vertical sliding pins 21 and 22 extend downwardly through guide holes 24 and 25 in the frame 23. These pins are arranged to slide vertically and permit vertical deflection adjustment of the forming board 12.

In accordance with the method of the invention the forming board is deflected or contoured along its length to the exact shape which will match the breast roll at any given operating condition so that the wire, carried by the breast roll, extends uniformly onto the forming board without being forced upwardly and without a gap occurring between the wire and the board. The defects of operation with structures heretofore available can be described in connection with FIGS. 4 and 5.

In FIG. 4 a forming board arrangement is shown wherein the upper surface of a forming board 34 is too high relative to the center of a breast roll 34. The ends of the breast roll are shown at 32a at the dotted lines, and the center is shown at 32 by the solid line, with the difference in elevation caused by the sag of the center of the breast roll 32. The wire 33 at the ends, as shown by the dotted line wire, properly engages the forming board 34. However at the center the wire has to be inclined upwardly to pass onto the forming board 34. Because of the stiffness and tension in the wire it will generally take the shape illustrated and curve upwardly at 33b so that stock on the wire tends to be thrown upwardly and the dewatering operation is consequently disturbed. Uniform dewatering at the beginning of formation of the web is particularly important since non-uniformity will cause non-uniformity of dryness at locations further along the machine. Efforts to compensate for the unevenness and dryness often result in imperfections in the paper and a papermaker noticing the unevenness may erroneously conclude that other parts of the machine are operating improperly so that it is highly important that web formation and dewaten'ng at the forming board begin satisfactorily.

FIG. illustrates an arrangement where the forming board is lowered to match the center of the breast roll. A breast roll 35 sags at the center as shown by the solid line drawing and is higher at the ends as shown at 35a. A forming board 37 is positioned so that the wire 36 approaches it uniformly at the center of the breast roll 35. This however results in the wire edge 36a at the ends of the breast roll having a clearance between it and the forming board 37 so that improper formation of the web occurs at the ends. As previously stated even though the forming board is initially attempted to be contoured in accordance with an initial sag in the breast roll, changes in operating conditions such as occur with normal changes in run in a paper mill including changes in operating speed, changes in types and consistency of stock and changes in wire tensions which occur through adjustment or through necessary changes in drive input torque with changes in suction box drag and other factors, will cause a variance in the deflection of the breast roll and the conditions of either FIG. 4 or 5.

As shown in FIGS. 1, 2 and 3, in one form of the invention the method and structure for changing the contour or deflection of the forming board includes the application of forces along the length of the forming board. The force applying means is shown as including expansible chambers in the form of fluid bellows 26 and 27. In

the arrangement shown the row of bellows 26 is arranged with individual bellows at spaced locations and the row of bellows 27 is arranged with individual bellows at spaced locations as is shown in FIG. 3 by the bellows 27a, 27b, 27c and 27d. Each bellows is equipped with an air pressure line which has a variable control valve in it so that the pressure within the bellows can be varied independent of the other bellows and thereby apply a force to obtain the proper deflection of the forming board 12 along its entire length. l l l The bellows 26 and 27 are mounted on the support frame 23 which is carried at its ends on hanger bars and 31. The hanger bars are supported on the main frame by hanger bar supports 28 and 29. The weight of the forming board 12 will cause it to bear downwardly against the bellows so that its vertical position will be a direct function of the upward force applied to it by each bellows. The pins 21 and 22 are freely slideable in the frame 23 so that regardless of the control position of the forming board 12, the board will remain straight across the machine and not deflect in the machine direction.

FIG. 6 illustrates another arrangement for applying the vertical forces to the forming board. A forming board assembly is shown with an upper member 41 having a smooth wire supporting surface at its top. The forming board assembly includes forward and rear walls 48 and 49 which are arranged to form a closed chamber within the forming board and partitions 50 and 51 separate the assembly into an upper fluid chamber 42 and a lower fluid chamber 43. These chambers are arranged with fluid connections so that a temperature differential can be maintained between them and the differences in expansion of the metal of the walls 48 and 49 at their top and bottom cause a deflection of the upper surface of the forming board 40. The upper chamber has an inlet 44 and an outlet 45, and the lower chamber has an inlet 46 and an outlet 47. In order to cause the forming board to deflect downwardly at its center cool water or refrigerant can be run into the top chamber 42 and hot water or steam placed in the lower chamber 43. While it is possible to deflect the upper surface of the forming board by merely cooling the upper chamber or heating the lower chamber, with the other chamber remaining substantially at room temperature, better control can be obtained by positively controlling the temperature of each of the chambers 42 and 43 for positive temperature differential and a positive resultant deflection of a forming board. It will be apparent from the foregoing that different heating and cooling arrangements can be used such as with electrical heating elements at the base of the forming board assembly and electrical cooling elements at the upper portion. For example thermo-couple elements may be used for his purpose.

In the arrangement of FIGS. 7 and 8 a vertical force is applied to the forming board by a weight. The weight is illustrated as conveniently applied by chambers for liquid beneath the members 60, 61 and 62 of the forming board means 55. The forming board is arranged so that tanks or chambers 63, 64 and 65 are a part of the assembly and are arranged so that a controlled quantity of liquid can be contained in each tank. Webs or plates 66 and 67 extend between the tanks, and baffles 68 extend through the tanks, the baffles being provided with openings 69 so that the liquid level remains the same across the tank.

Liquid such as water is directed into the tank through a supply line 75 through an inlet 72. The tank can be drained through a valve outlet 74. An air vent 76 at the top of the tank permits the level to be changed.

The tank assembly is supported on a main frame by hangers 70 and 71 which are positioned so that the ends of the upper surface of the forming board are at the proper location relative to the ends of the breast roll.

As the breast roll deflects with changes in operating conditions the quantity of liquid within the forming board tanks is changed accordingly.

Thus it will be seen that I have provided an improved method and apparatus for obtaining the objectives and advantages above set forth. By applying controlled forces to the forming board and controlling its deflection while maintaining it straight across the machine improved paper formation results and defects of structures and methods heretofore available are obviated.

The drawings and specification present a detailed disclosure of the preferred embodiments of the invention, and it is to be understood that the invention is not limited to the specific forms disclosed, but covers all modifications, changes and alternative constructions and methods falling within the scope of the principles taught by the invention.

I claim as my invention:

1. In a papermaking machine, the combination comprising, a pervious travelling forming wire having an upper forming run, a breast roll supporting the wire at the lead end of said run, a forming board means spaced from the breast roll having an upper surface beneath the forming wire having a length which extends transversely across the wire, and

means for imparting a lengthwise deflection to said board and to change the deflection of said board means upper surface along its transverse length to generally conform to any deflection of the breast roll.

2. In a papermaking machine the combination in accordance with claim 1 wherein said board means is supported at its ends and said changing means applies a variable controlled force to the board means for changing the deflection intermediate the ends.

'3. Elm a papermaking machine the combination in accordance with claim 1 wherein said changing means includes force applying means along the length of said board means applying controlled forces to the board means.

4. In a papermaking machine the combination in accordance with claim 3 wherein said force applying means includes a plurality of expansible pressure chambers each having a movable Wall contacting the board means for applying a force therealong controlling the deflection proportional to the applied force.

5. In a papermaking machine the combination in accordance with claim 3 wherein said force applying means includes a plurality of expansible bellows each with a fluid pressure line, and means for delivering pressure to said lines at individually controlled pressures.

6. In a papermaking machine the combination in accordance with claim 1 wherein said changing means includes first and second temperature elements rigidly connected to said board means with deflection of the board means changing as the temperature differential between said first and second elements changes, and means for controllably changing the temperature of at least one of said temperature elements.

7. In a papermaking machine the combination in accordance with claim 6 wherein said temperature elements extend longitudinally along said forming board means and are hollow for the receipt of fluid at different temperatures, and means for delivering fluid at different temperatures to said hollow temperature elements.

'8. In a papermaking machine the combination in accordance with claim 1 wherein said changing means includes means for applying weight along the length of the board means for controlling the force applied.

9. In a papermaking machine the combination in accordance with claim 2 wherein said changing means includes a chamber means extending along the length of the board means for containing a liquid, and means for changing the quantity of liquid in said chamber means.

10. In a papermaking machine including a travelling forming wire with an upper forming run,

breast rolls supporting the wire and a forming board means spaced from the breast roll and with its length extending transversely to said wire generally parallel to said breast roll,

said forming board means tending to deflect with changes in operating factors, the method of positively controlling the deflection of the upper surface of the forming board means including the steps of applying a positive control force along the length of the forming board means to change its deflection with change in deflection of the breast roll independent of stock flow rate and quantity and independent of wire tension.

11. The method of claim 10 wherein the deflection is varied by applying separate vertical forces to the board means along its length and independently changing the forces.

12. The method of claim 10 wherein the deflection is obtained by controlling the temperature of the forming board means at different locations and maintaining a temperature differential in an amount which causes a deflection of the board means to a desired amount.

13. The method of claim 10 wherein a vertical weight is applied to the board means and the weight is changed a desired amount for obtaining the deflection required.

References Cited UNITED STATES PATENTS 3,017,930 1/1962 Dunlap 162-352 3,201,308 8/1965 Goddard et al 162374X 3,323,981 6/1967 Heys 162-352 3,393,124 7/1968 Klingler et al 162-352 3,313,681 4/1967 Dennis et a1 162336X REUBEN FRIEDMAN, Primary Examiner T. A. GRANGER, Assistant Examiner U.S. Cl. X.R. 162-352 

